Question

Consider the following reaction in an aqueous solution:

$I^{-}\left(aq\right)+OC{l}^{-}\to I{O}^{-}\left(aq\right)+C{l}^{-}\left(aq\right)$

The initial concentration and initial rate for this reaction are given:

Exp. No	$\left[I^{-}\right]M$	$\left[OC{l}^{-}\right]M$	Initial rate
$1.$	$0.1000$	$0.0500$	$3.05\times 1$
$2.$	$0.2000$	$0.0500$	$6.10\times 1$
$3.$	$0.3000$	$0.0100$	$1.83\times 1$
$4.$	$0.3000$	$0.0200$	$3.66\times 1$

Which of the following is the correct rate for this reaction?

• A. $Rate=k\left[I^{-}{]}^2\right[OC{l}^{-}]$
• B. $Rate=k\left[OC{l}^{-}\right]$
• C. $Rate=k[I^{-}{]}^2$
• D. $Rate=k\left[I^{-}\right]\left[OC{l}^{-}\right]$

Answer 1

The correct option is D $Rate=k\left[I^{-}\right]\left[OC{l}^{-}\right]$

From experiment no $3$ and $4$, doubling $\left[OC{l}^{-}\right]$ doubles the rate; i.e., order with respect to $OC{l}^{-}$ is one.

Also, from experiment no $1$ and $2$, doubles the concentration of $\left[I^{-}\right]$ double the rate, i.e. order with respect to $I^{-}$ is also one.

$rate=k\left[I^{-}\right]\left[OC{l}^{-}\right]$.

Hence, option D is correct.